Imperial College London
Alternate

ProfessorJi-SeonKim

Faculty of Natural Sciences, Department of Physics

Professor of Solid State Physics
 
 
 
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Contact

 

+44 (0)20 7594 7597ji-seon.kim

 
 
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Location

 

B909Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Kim:2019:10.1002/admi.201801763,
author = {Kim, J-S},
doi = {10.1002/admi.201801763},
journal = {Advanced Materials Interfaces},
title = {Impact of initial bulk-heterojunction morphology on operational stability of polymer:fullerene photovoltaic cells},
url = {http://dx.doi.org/10.1002/admi.201801763},
volume = {6},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Controlling initial bulk-heterojunction (BHJ) morphology is critical for device performance of organic photovoltaic (OPV) cells. However, its impact on performance, specifically long-term operational stability is still poorly understood. This is mainly due to limitations in direct measurements enabling in-situ monitoring of devices at a molecular level. Here, we utilize thermal annealing preconditioning step to tune initial morphology of model polymer:fullerene BHJ OPV devices and molecular resonant vibrational spectroscopy to identify in-situ degradation pathways. We report direct spectroscopic evidence for molecular-scale phase segregation temperature (TPS) which critically determines a boundary in high efficiency and long operational stability. Under operation, initially well-mixed blend morphology (no annealing) shows interface instability related to the hole-extracting PEDOT:PSS layer via de-doping. Likewise, initially phase-segregatedmorphology at a molecular level (annealed above TPS) shows instability in the photoactive layer via continuous phase segregation between polymer and fullerenes in macroscales, coupled with further fullerene photodegradation. Our results confirm that a thermal annealing preconditioning step is  essential to stabilize the BHJ morphology; in particular annealing below TPS is critical for improved operational stability whilst maintaining high efficiency.
AU  - Kim,J-S
DO  - 10.1002/admi.201801763
PY  - 2019///
SN  - 2196-7350
TI  - Impact of initial bulk-heterojunction morphology on operational stability of polymer:fullerene photovoltaic cells
T2  - Advanced Materials Interfaces
UR  - http://dx.doi.org/10.1002/admi.201801763
UR  - http://hdl.handle.net/10044/1/65759
VL  - 6
ER  -
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